These memory traces were gathered from a set of servers, desktops, and laptops 
in the UMass CS Department.  Each trace file contains a list of hashes 
representing the contents of the machine's memory, as well as some meta 
information about the running processes and OS type.

The traces have been grouped by type and date.  So far we have released traces 
from a set of macbooks running OS X 10.5 and a set of four linux web/email 
servers.  Tar files have been provided for each day of the week from September 
7-13, 2008.  Traces were recorded approximately every 30 minutes, although if 
machines were turned off or away from an internet connection for a long period, 
no traces were acquired.


Each trace file is split into two portions.  The top segment is ASCII text 
containing the system meta data about operating system type and a list of 
running processes.  This is followed by binary data containing the list of 
hashes generated for each page in the system.  Hashes are stored as consecutive 
32bit values.  Some files also contain a Bloom Filter segment after the hash 
list, this can be ignored.

We are providing a simple tool, traceReader.c, for extracting the hashes from a 
trace file.  This takes as an argument the file to be parsed, and will output 
the hash list as a series of integer values.  For example to extract the hashes 
from "trace-x.dat" you would run:
./traceReader trace-x.dat > trace-x

If you would like to compare to traces to estimate the amount of sharing 
between them, you could run:
./traceReader trace-x.dat > trace-all
./traceReader trace-y.dat >> trace-all
cat tmp | sort | uniq -c

This will tell you the number of times that each hash occurs in the system.

For more information on the trace files and the memory tracer used to generate 
them, please refer to the paper:

Timothy Wood, Gabriel Tarasuk-Levin, Prashant Shenoy, Peter Desnoyers, Emmanuel 
Cecchet, and Mark Corner. Memory Buddies: Exploiting Page Sharing for Smart 
Colocation in Virtualized Data Centers.  In proceedings of the International 
Conference on Virtual Execution Environments, VEE 2009

http://lass.cs.umass.edu/papers/pdf/VEE09-membuds.pdf

Please cite the paper above if you use these traces in your own work.  This
trace collection research was supported in part by NSF grant CNS-0720271

Direct any questions or comments to Tim Wood --- twood@cs.umass.edu